1. Field of the Invention
The present invention relates to compressors and other fluid pumps, and particularly to a fluid pump apparatus that is powered by an electromagnetic drive system.
2. Discussion of the Prior Art
Refrigeration-cycle systems are used to provide cooling in everything from automobile air conditioners to commercial freezers such as those employed to cool refrigerated or frozen-food counters in grocery stores. A conventional system includes a condenser, an evaporator, liquid and suction lines connected between the condenser and the evaporator to form a closed coolant system, a compressor, and a thermostatic expansion valve in the liquid line adjacent the evaporator.
The compressor of a conventional refrigeration-cycle system is typically driven by a belt or other power takeoff mechanism connected between the compressor and a motor, and operates only in a fully on or off position. As a result, it is necessary to repeatedly turn the compressor on and off as needed, and it is not possible to simply slow operation of the compressor as desired.
This drawback of conventional compressors is evident in automobile air conditioners, where operation of the compressor in the fully on position presents a drain to the rest of the system which is perceptible to the driver as a loss of power. Because the compressor turns on and off automatically during operation of the air conditioner, surges and declines in the power of the automobile are unpredictable and can complicate operation of the vehicle.
Other drawbacks experienced in the use of conventional compressors include the need for frequent lubrication of the compressor parts, and the inability to permit easy assembly and repair of the compressor. In addition, conventional compressors are not well equipped to handle liquid in the gas line of the system. When liquid enters a conventional compressor, it prevents the pistons of the compressor from reaching the ends of their strokes, causing failure of the piston rods or crank shaft of the compressor.